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<pre><span class="sourceLineNo">001</span><a name="line.1"></a>
<span class="sourceLineNo">002</span>/*<a name="line.2"></a>
<span class="sourceLineNo">003</span> * Copyright (C) 2012 Archie L. Cobbs. All rights reserved.<a name="line.3"></a>
<span class="sourceLineNo">004</span> *<a name="line.4"></a>
<span class="sourceLineNo">005</span> * $Id: Synchronizer.html 947 2014-11-12 22:14:09Z archie.cobbs $<a name="line.5"></a>
<span class="sourceLineNo">006</span> */<a name="line.6"></a>
<span class="sourceLineNo">007</span><a name="line.7"></a>
<span class="sourceLineNo">008</span>package org.dellroad.stuff.pobj.distrib;<a name="line.8"></a>
<span class="sourceLineNo">009</span><a name="line.9"></a>
<span class="sourceLineNo">010</span>import java.io.File;<a name="line.10"></a>
<span class="sourceLineNo">011</span>import java.util.ArrayList;<a name="line.11"></a>
<span class="sourceLineNo">012</span>import java.util.Date;<a name="line.12"></a>
<span class="sourceLineNo">013</span>import java.util.List;<a name="line.13"></a>
<span class="sourceLineNo">014</span><a name="line.14"></a>
<span class="sourceLineNo">015</span>import org.dellroad.stuff.pobj.PersistentObject;<a name="line.15"></a>
<span class="sourceLineNo">016</span>import org.dellroad.stuff.pobj.PersistentObjectEvent;<a name="line.16"></a>
<span class="sourceLineNo">017</span>import org.dellroad.stuff.pobj.PersistentObjectException;<a name="line.17"></a>
<span class="sourceLineNo">018</span>import org.dellroad.stuff.pobj.PersistentObjectListener;<a name="line.18"></a>
<span class="sourceLineNo">019</span>import org.dellroad.stuff.pobj.PersistentObjectVersionException;<a name="line.19"></a>
<span class="sourceLineNo">020</span>import org.dellroad.stuff.spring.AbstractBean;<a name="line.20"></a>
<span class="sourceLineNo">021</span><a name="line.21"></a>
<span class="sourceLineNo">022</span>/**<a name="line.22"></a>
<span class="sourceLineNo">023</span> * Synchronizes a {@link PersistentObject} database across multiple nodes using {@code git(1)}.<a name="line.23"></a>
<span class="sourceLineNo">024</span> *<a name="line.24"></a>
<span class="sourceLineNo">025</span> * &lt;p&gt;<a name="line.25"></a>
<span class="sourceLineNo">026</span> * This class provides a simple and lightweight way to build a "master-master" multi-node database<a name="line.26"></a>
<span class="sourceLineNo">027</span> * based on {@link PersistentObject} object graphs. The basic idea is to apply {@code git(1)}'s<a name="line.27"></a>
<span class="sourceLineNo">028</span> * efficient communication protocol and powerful merging algorithms to the {@link PersistentObject}<a name="line.28"></a>
<span class="sourceLineNo">029</span> * database's XML representation. As a result, all nodes can make simultaneous changes, updates are<a name="line.29"></a>
<span class="sourceLineNo">030</span> * communicated quickly, and in only a small corner case -- two conflicting changes to the same<a name="line.30"></a>
<span class="sourceLineNo">031</span> * data element applied at virtually same time -- must one node's change "win" and the other's "lose".<a name="line.31"></a>
<span class="sourceLineNo">032</span> * No global communication or two-phase commit protocol is required, and recovery from arbitrary<a name="line.32"></a>
<span class="sourceLineNo">033</span> * network problems is automatic.<a name="line.33"></a>
<span class="sourceLineNo">034</span> * &lt;/p&gt;<a name="line.34"></a>
<span class="sourceLineNo">035</span> *<a name="line.35"></a>
<span class="sourceLineNo">036</span> * &lt;p&gt;<a name="line.36"></a>
<span class="sourceLineNo">037</span> * This class works by registering as a {@linkplain PersistentObjectListener listener} on a {@link PersistentObject}<a name="line.37"></a>
<span class="sourceLineNo">038</span> * and also managing a private {@code git(1)} repository which is configured to track zero or more remotes.<a name="line.38"></a>
<span class="sourceLineNo">039</span> * Each time a change occurs to the {@link PersistentObject} database, an updated XML copy of the database<a name="line.39"></a>
<span class="sourceLineNo">040</span> * is committed to the {@code git(1)} repository, and then &lt;i&gt;synchronization&lt;/i&gt; is performed: all remotes are fetched<a name="line.40"></a>
<span class="sourceLineNo">041</span> * and their corresponding {@code git(1)} branches merged into the local {@code git(1)} branch (this process<a name="line.41"></a>
<span class="sourceLineNo">042</span> * is performed by {@link #synchronize}). During synchronization, several merge strategies are tried until an XML file<a name="line.42"></a>
<span class="sourceLineNo">043</span> * is produced that {@linkplain org.dellroad.stuff.pobj.PersistentObjectDelegate#validate validates}.<a name="line.43"></a>
<span class="sourceLineNo">044</span> * If synchronization results in a non-trivial merge (i.e., any changes), the local {@link PersistentObject} is updated<a name="line.44"></a>
<span class="sourceLineNo">045</span> * with the result and therefore made aware of the other nodes' changes. In this way, all nodes have their<a name="line.45"></a>
<span class="sourceLineNo">046</span> * {@link PersistentObject} databases automatically synchronized and merged as they evolve.<a name="line.46"></a>
<span class="sourceLineNo">047</span> * &lt;/p&gt;<a name="line.47"></a>
<span class="sourceLineNo">048</span> *<a name="line.48"></a>
<span class="sourceLineNo">049</span> * &lt;p&gt;<a name="line.49"></a>
<span class="sourceLineNo">050</span> * The user of this class must separately initialize each node's {@code git(1)} repository, configure the<a name="line.50"></a>
<span class="sourceLineNo">051</span> * {@linkplain #setRemotes remotes}, and determine when to {@link #synchronize} remote changes:<a name="line.51"></a>
<span class="sourceLineNo">052</span> * as mentioned above, synchronization is performed automatically when the local {@link PersistentObject} database changes,<a name="line.52"></a>
<span class="sourceLineNo">053</span> * but for remote changes either some external notification process must trigger a call to {@link #synchronize},<a name="line.53"></a>
<span class="sourceLineNo">054</span> * or {@link #synchronize} must be invoked at regular intervals, or (for robustness in the face of transient<a name="line.54"></a>
<span class="sourceLineNo">055</span> * network issues) both.<a name="line.55"></a>
<span class="sourceLineNo">056</span> * &lt;/p&gt;<a name="line.56"></a>
<span class="sourceLineNo">057</span> *<a name="line.57"></a>
<span class="sourceLineNo">058</span> * &lt;p&gt;<a name="line.58"></a>
<span class="sourceLineNo">059</span> * Merges are handled by {@link #merge merge()} (which subclasses may override if desired). The {@link #merge merge}<a name="line.59"></a>
<span class="sourceLineNo">060</span> * implementation in this class attempts merges using the following strategies in order until there are no merge<a name="line.60"></a>
<span class="sourceLineNo">061</span> * conflicts and a {@linkplain org.dellroad.stuff.pobj.PersistentObjectDelegate#validate valid} XML file is achieved:<a name="line.61"></a>
<span class="sourceLineNo">062</span> *  &lt;ul&gt;<a name="line.62"></a>
<span class="sourceLineNo">063</span> *  &lt;li&gt;Recursive merge using the patience algorithm&lt;/li&gt;<a name="line.63"></a>
<span class="sourceLineNo">064</span> *  &lt;li&gt;Same as previous, but resolving all conflicts one way or the other&lt;/li&gt;<a name="line.64"></a>
<span class="sourceLineNo">065</span> *  &lt;li&gt;Simply choosing one file or the other&lt;/li&gt;<a name="line.65"></a>
<span class="sourceLineNo">066</span> *  &lt;/ul&gt;<a name="line.66"></a>
<span class="sourceLineNo">067</span> * &lt;/p&gt;<a name="line.67"></a>
<span class="sourceLineNo">068</span> *<a name="line.68"></a>
<span class="sourceLineNo">069</span> * &lt;p&gt;<a name="line.69"></a>
<span class="sourceLineNo">070</span> * If conflicts occur in attempt #1, but attempt #2 or #3 succeeds and the other node is the "winner", then<a name="line.70"></a>
<span class="sourceLineNo">071</span> * {@link #handleConflictOverride handleConflictOverride()} is invoked to notify the local node that some of<a name="line.71"></a>
<span class="sourceLineNo">072</span> * its recent changes have been overridden; if all three attempts fail, then<a name="line.72"></a>
<span class="sourceLineNo">073</span> * {@link #handleImpossibleMerge handleImpossibleMerge()} is invoked and we stay with whatever version we are on;<a name="line.73"></a>
<span class="sourceLineNo">074</span> * this latter case can only occur when another node is running a different version of the software<a name="line.74"></a>
<span class="sourceLineNo">075</span> * (with different validation criteria).<a name="line.75"></a>
<span class="sourceLineNo">076</span> * &lt;/p&gt;<a name="line.76"></a>
<span class="sourceLineNo">077</span> *<a name="line.77"></a>
<span class="sourceLineNo">078</span> * &lt;p&gt;<a name="line.78"></a>
<span class="sourceLineNo">079</span> * For attempts #2 and #3, the "winner" is chosen by {@link #chooseConflictWinner chooseConflictWinner()} as follows:<a name="line.79"></a>
<span class="sourceLineNo">080</span> *  &lt;ul&gt;<a name="line.80"></a>
<span class="sourceLineNo">081</span> *  &lt;li&gt;If the commits have different timestamps, then the later commit wins&lt;/li&gt;<a name="line.81"></a>
<span class="sourceLineNo">082</span> *  &lt;li&gt;If the two commits were simultaneous, then the commit with the lexicographically higher SHA-1 checksum wins&lt;/li&gt;<a name="line.82"></a>
<span class="sourceLineNo">083</span> *  &lt;li&gt;If the two commits have the same timestamp and SHA-1 checksum, then there won't be any conflicts :)&lt;/li&gt;<a name="line.83"></a>
<span class="sourceLineNo">084</span> *  &lt;/ul&gt;<a name="line.84"></a>
<span class="sourceLineNo">085</span> * &lt;/p&gt;<a name="line.85"></a>
<span class="sourceLineNo">086</span> *<a name="line.86"></a>
<span class="sourceLineNo">087</span> * &lt;p&gt;<a name="line.87"></a>
<span class="sourceLineNo">088</span> * Subclasses may {@linkplain #chooseConflictWinner override how the winner is chosen}.<a name="line.88"></a>
<span class="sourceLineNo">089</span> * &lt;/p&gt;<a name="line.89"></a>
<span class="sourceLineNo">090</span> *<a name="line.90"></a>
<span class="sourceLineNo">091</span> * &lt;p&gt;<a name="line.91"></a>
<span class="sourceLineNo">092</span> * Because all nodes follow this same algorithm for merging, they will all end up with the same result<a name="line.92"></a>
<span class="sourceLineNo">093</span> * (note however that the {@link PersistentObject} object graph must serialize in a deterministic way for this to be true).<a name="line.93"></a>
<span class="sourceLineNo">094</span> * &lt;/p&gt;<a name="line.94"></a>
<span class="sourceLineNo">095</span> *<a name="line.95"></a>
<span class="sourceLineNo">096</span> * &lt;p&gt;<a name="line.96"></a>
<span class="sourceLineNo">097</span> * Note that merge conflicts can only happen when two nodes make changes at virtually the same time (or, when<a name="line.97"></a>
<span class="sourceLineNo">098</span> * separated by a network partition): i.e., a change on one node occurs within the window of time after a change<a name="line.98"></a>
<span class="sourceLineNo">099</span> * is made on another node but before the first node is notified and synchronizes. Using a simple<a name="line.99"></a>
<span class="sourceLineNo">100</span> * real-time notification process, this window can be kept small, especially relative to the frequent-read,<a name="line.100"></a>
<span class="sourceLineNo">101</span> * infrequent-write access pattern that the {@link PersistentObject} class is designed for. When a conflict override<a name="line.101"></a>
<span class="sourceLineNo">102</span> * does occur, subclasses can override {@link #handleConflictOverride handleConflictOverride()} to take appropriate action.<a name="line.102"></a>
<span class="sourceLineNo">103</span> * &lt;/p&gt;<a name="line.103"></a>
<span class="sourceLineNo">104</span> *<a name="line.104"></a>
<span class="sourceLineNo">105</span> * &lt;p&gt;<a name="line.105"></a>
<span class="sourceLineNo">106</span> * Instances of this class are thread safe.<a name="line.106"></a>
<span class="sourceLineNo">107</span> * &lt;/p&gt;<a name="line.107"></a>
<span class="sourceLineNo">108</span> *<a name="line.108"></a>
<span class="sourceLineNo">109</span> * @param &lt;T&gt; type of the root object<a name="line.109"></a>
<span class="sourceLineNo">110</span> */<a name="line.110"></a>
<span class="sourceLineNo">111</span>public class Synchronizer&lt;T&gt; extends AbstractBean implements PersistentObjectListener&lt;T&gt; {<a name="line.111"></a>
<span class="sourceLineNo">112</span><a name="line.112"></a>
<span class="sourceLineNo">113</span>    /**<a name="line.113"></a>
<span class="sourceLineNo">114</span>     * Default value for the XML file that is stored in the {@code git(1)} repository ({@value #DEFAULT_FILENAME}).<a name="line.114"></a>
<span class="sourceLineNo">115</span>     */<a name="line.115"></a>
<span class="sourceLineNo">116</span>    public static final String DEFAULT_FILENAME = "root.xml";<a name="line.116"></a>
<span class="sourceLineNo">117</span><a name="line.117"></a>
<span class="sourceLineNo">118</span>    /**<a name="line.118"></a>
<span class="sourceLineNo">119</span>     * Default value for the {@code git(1)} {@linkplain #setBranch branch} name ({@value #DEFAULT_BRANCH}).<a name="line.119"></a>
<span class="sourceLineNo">120</span>     */<a name="line.120"></a>
<span class="sourceLineNo">121</span>    public static final String DEFAULT_BRANCH = "master";<a name="line.121"></a>
<span class="sourceLineNo">122</span><a name="line.122"></a>
<span class="sourceLineNo">123</span>    /**<a name="line.123"></a>
<span class="sourceLineNo">124</span>     * The associated {@link PersistentObject}.<a name="line.124"></a>
<span class="sourceLineNo">125</span>     */<a name="line.125"></a>
<span class="sourceLineNo">126</span>    protected PersistentObject&lt;T&gt; persistentObject;<a name="line.126"></a>
<span class="sourceLineNo">127</span><a name="line.127"></a>
<span class="sourceLineNo">128</span>    /**<a name="line.128"></a>
<span class="sourceLineNo">129</span>     * Our associated {@code git(1)} repository.<a name="line.129"></a>
<span class="sourceLineNo">130</span>     */<a name="line.130"></a>
<span class="sourceLineNo">131</span>    protected GitRepository git;<a name="line.131"></a>
<span class="sourceLineNo">132</span><a name="line.132"></a>
<span class="sourceLineNo">133</span>    /**<a name="line.133"></a>
<span class="sourceLineNo">134</span>     * The name of our XML file in the {@code git(1)} repository.<a name="line.134"></a>
<span class="sourceLineNo">135</span>     */<a name="line.135"></a>
<span class="sourceLineNo">136</span>    protected String filename = DEFAULT_FILENAME;<a name="line.136"></a>
<span class="sourceLineNo">137</span><a name="line.137"></a>
<span class="sourceLineNo">138</span>    /**<a name="line.138"></a>
<span class="sourceLineNo">139</span>     * The name for the {@code git(1)} branches we manage.<a name="line.139"></a>
<span class="sourceLineNo">140</span>     */<a name="line.140"></a>
<span class="sourceLineNo">141</span>    protected String branch = DEFAULT_BRANCH;<a name="line.141"></a>
<span class="sourceLineNo">142</span><a name="line.142"></a>
<span class="sourceLineNo">143</span>    /**<a name="line.143"></a>
<span class="sourceLineNo">144</span>     * The names of the {@code git(1)} remotes we should synchronize with.<a name="line.144"></a>
<span class="sourceLineNo">145</span>     */<a name="line.145"></a>
<span class="sourceLineNo">146</span>    protected List&lt;String&gt; remotes;<a name="line.146"></a>
<span class="sourceLineNo">147</span><a name="line.147"></a>
<span class="sourceLineNo">148</span>    /**<a name="line.148"></a>
<span class="sourceLineNo">149</span>     * Configure the {@link PersistentObject} that this instance will interact with.<a name="line.149"></a>
<span class="sourceLineNo">150</span>     *<a name="line.150"></a>
<span class="sourceLineNo">151</span>     * &lt;p&gt;<a name="line.151"></a>
<span class="sourceLineNo">152</span>     * Required property.<a name="line.152"></a>
<span class="sourceLineNo">153</span>     * &lt;/p&gt;<a name="line.153"></a>
<span class="sourceLineNo">154</span>     */<a name="line.154"></a>
<span class="sourceLineNo">155</span>    public void setPersistentObject(PersistentObject&lt;T&gt; persistentObject) {<a name="line.155"></a>
<span class="sourceLineNo">156</span>        this.persistentObject = persistentObject;<a name="line.156"></a>
<span class="sourceLineNo">157</span>    }<a name="line.157"></a>
<span class="sourceLineNo">158</span><a name="line.158"></a>
<span class="sourceLineNo">159</span>    /**<a name="line.159"></a>
<span class="sourceLineNo">160</span>     * Configure the {@code git(1)} repository location. The repository, branches, and remotes must already exist.<a name="line.160"></a>
<span class="sourceLineNo">161</span>     *<a name="line.161"></a>
<span class="sourceLineNo">162</span>     * &lt;p&gt;<a name="line.162"></a>
<span class="sourceLineNo">163</span>     * Note that multiple instances of this class can share the same {@link GitRepository} as long as they<a name="line.163"></a>
<span class="sourceLineNo">164</span>     * are configured with different {@linkplain #setBranch branches}.<a name="line.164"></a>
<span class="sourceLineNo">165</span>     * &lt;/p&gt;<a name="line.165"></a>
<span class="sourceLineNo">166</span>     *<a name="line.166"></a>
<span class="sourceLineNo">167</span>     * &lt;p&gt;<a name="line.167"></a>
<span class="sourceLineNo">168</span>     * Required property.<a name="line.168"></a>
<span class="sourceLineNo">169</span>     * &lt;/p&gt;<a name="line.169"></a>
<span class="sourceLineNo">170</span>     *<a name="line.170"></a>
<span class="sourceLineNo">171</span>     * @param git {@code git(1)} repository<a name="line.171"></a>
<span class="sourceLineNo">172</span>     */<a name="line.172"></a>
<span class="sourceLineNo">173</span>    public void setGitRepository(GitRepository git) {<a name="line.173"></a>
<span class="sourceLineNo">174</span>        this.git = git;<a name="line.174"></a>
<span class="sourceLineNo">175</span>    }<a name="line.175"></a>
<span class="sourceLineNo">176</span><a name="line.176"></a>
<span class="sourceLineNo">177</span>    /**<a name="line.177"></a>
<span class="sourceLineNo">178</span>     * Configure the name of the XML file in the {@code git(1)} repository.<a name="line.178"></a>
<span class="sourceLineNo">179</span>     *<a name="line.179"></a>
<span class="sourceLineNo">180</span>     * &lt;p&gt;<a name="line.180"></a>
<span class="sourceLineNo">181</span>     * Default value is {@value #DEFAULT_FILENAME}.<a name="line.181"></a>
<span class="sourceLineNo">182</span>     * &lt;/p&gt;<a name="line.182"></a>
<span class="sourceLineNo">183</span>     *<a name="line.183"></a>
<span class="sourceLineNo">184</span>     * @param filename XML file name<a name="line.184"></a>
<span class="sourceLineNo">185</span>     */<a name="line.185"></a>
<span class="sourceLineNo">186</span>    public void setFilename(String filename) {<a name="line.186"></a>
<span class="sourceLineNo">187</span>        this.filename = filename;<a name="line.187"></a>
<span class="sourceLineNo">188</span>    }<a name="line.188"></a>
<span class="sourceLineNo">189</span><a name="line.189"></a>
<span class="sourceLineNo">190</span>    /**<a name="line.190"></a>
<span class="sourceLineNo">191</span>     * Configure name of the {@code git(1)} branches we will manage.<a name="line.191"></a>
<span class="sourceLineNo">192</span>     *<a name="line.192"></a>
<span class="sourceLineNo">193</span>     * &lt;p&gt;<a name="line.193"></a>
<span class="sourceLineNo">194</span>     * The same branch name is used for all nodes in the cluster, local and remote, so<a name="line.194"></a>
<span class="sourceLineNo">195</span>     * this name identifes both the local branch representing this node's root and each<a name="line.195"></a>
<span class="sourceLineNo">196</span>     * remote's branch that we track and merge from.<a name="line.196"></a>
<span class="sourceLineNo">197</span>     * &lt;/p&gt;<a name="line.197"></a>
<span class="sourceLineNo">198</span>     *<a name="line.198"></a>
<span class="sourceLineNo">199</span>     * &lt;p&gt;<a name="line.199"></a>
<span class="sourceLineNo">200</span>     * Value must match {@link GitRepository#BRANCH_NAME_PATTERN}.<a name="line.200"></a>
<span class="sourceLineNo">201</span>     * &lt;/p&gt;<a name="line.201"></a>
<span class="sourceLineNo">202</span>     *<a name="line.202"></a>
<span class="sourceLineNo">203</span>     * &lt;p&gt;<a name="line.203"></a>
<span class="sourceLineNo">204</span>     * Default value is {@value #DEFAULT_BRANCH}.<a name="line.204"></a>
<span class="sourceLineNo">205</span>     * &lt;/p&gt;<a name="line.205"></a>
<span class="sourceLineNo">206</span>     *<a name="line.206"></a>
<span class="sourceLineNo">207</span>     * @param branch branch name<a name="line.207"></a>
<span class="sourceLineNo">208</span>     */<a name="line.208"></a>
<span class="sourceLineNo">209</span>    public void setBranch(String branch) {<a name="line.209"></a>
<span class="sourceLineNo">210</span>        this.branch = branch;<a name="line.210"></a>
<span class="sourceLineNo">211</span>    }<a name="line.211"></a>
<span class="sourceLineNo">212</span><a name="line.212"></a>
<span class="sourceLineNo">213</span>    /**<a name="line.213"></a>
<span class="sourceLineNo">214</span>     * Configure the names of the {@code git(1)} remotes we will synchronize with.<a name="line.214"></a>
<span class="sourceLineNo">215</span>     * Note: these are {@code git(1)} remote names, not {@code git(1)} branch names; the same<a name="line.215"></a>
<span class="sourceLineNo">216</span>     * {@linkplain #setBranch branch} is used for all nodes in the cluster, local and remote.<a name="line.216"></a>
<span class="sourceLineNo">217</span>     * &lt;/p&gt;<a name="line.217"></a>
<span class="sourceLineNo">218</span>     *<a name="line.218"></a>
<span class="sourceLineNo">219</span>     * &lt;p&gt;<a name="line.219"></a>
<span class="sourceLineNo">220</span>     * Each value must match {@link GitRepository#REMOTE_NAME_PATTERN}.<a name="line.220"></a>
<span class="sourceLineNo">221</span>     * &lt;/p&gt;<a name="line.221"></a>
<span class="sourceLineNo">222</span>     *<a name="line.222"></a>
<span class="sourceLineNo">223</span>     * &lt;p&gt;<a name="line.223"></a>
<span class="sourceLineNo">224</span>     * Required property.<a name="line.224"></a>
<span class="sourceLineNo">225</span>     * &lt;/p&gt;<a name="line.225"></a>
<span class="sourceLineNo">226</span>     */<a name="line.226"></a>
<span class="sourceLineNo">227</span>    public synchronized void setRemotes(List&lt;String&gt; remotes) {<a name="line.227"></a>
<span class="sourceLineNo">228</span>        this.remotes = remotes;<a name="line.228"></a>
<span class="sourceLineNo">229</span>    }<a name="line.229"></a>
<span class="sourceLineNo">230</span><a name="line.230"></a>
<span class="sourceLineNo">231</span>    @Override<a name="line.231"></a>
<span class="sourceLineNo">232</span>    public void afterPropertiesSet() throws Exception {<a name="line.232"></a>
<span class="sourceLineNo">233</span>        super.afterPropertiesSet();<a name="line.233"></a>
<span class="sourceLineNo">234</span><a name="line.234"></a>
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<span class="sourceLineNo">237</span>            throw new Exception("no PersistentObject configured");<a name="line.237"></a>
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<span class="sourceLineNo">239</span>            throw new Exception("no GitRepository configured");<a name="line.239"></a>
<span class="sourceLineNo">240</span>        if (this.filename == null)<a name="line.240"></a>
<span class="sourceLineNo">241</span>            throw new Exception("no filename configured");<a name="line.241"></a>
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<span class="sourceLineNo">243</span>            throw new Exception("no branch name configured");<a name="line.243"></a>
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<span class="sourceLineNo">245</span>            throw new Exception("illegal branch name `" + this.branch + "'");<a name="line.245"></a>
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<span class="sourceLineNo">247</span>            throw new Exception("no remotes configured");<a name="line.247"></a>
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<span class="sourceLineNo">250</span>                throw new Exception("illegal remote name `" + remote + "'");<a name="line.250"></a>
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<span class="sourceLineNo">263</span>        this.persistentObject.removeListener(this);<a name="line.263"></a>
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<span class="sourceLineNo">269</span>     * Handle notification of a change to the local root.<a name="line.269"></a>
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<span class="sourceLineNo">271</span>     * &lt;p&gt;<a name="line.271"></a>
<span class="sourceLineNo">272</span>     * The implementation in {@link Synchronizer} delegates to {@link #applyLocalUpdate}.<a name="line.272"></a>
<span class="sourceLineNo">273</span>     * &lt;/p&gt;<a name="line.273"></a>
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<span class="sourceLineNo">276</span>    public void handleEvent(PersistentObjectEvent&lt;T&gt; event) {<a name="line.276"></a>
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<span class="sourceLineNo">278</span>          "Update after local change (version " + event.getVersion() + ")");<a name="line.278"></a>
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<span class="sourceLineNo">282</span>     * Given a (possibly) updated local root, {@linkplain #commit commit} it to our local branch,<a name="line.282"></a>
<span class="sourceLineNo">283</span>     * {@link #synchronize} with our peers if it represented a change, and apply the newly merged<a name="line.283"></a>
<span class="sourceLineNo">284</span>     * root (if any) back to the associated {@link PersistentObject}.<a name="line.284"></a>
<span class="sourceLineNo">285</span>     *<a name="line.285"></a>
<span class="sourceLineNo">286</span>     * &lt;p&gt;<a name="line.286"></a>
<span class="sourceLineNo">287</span>     * This method is invoked at {@linkplain #afterPropertiesSet startup} and after {@linkplain #handleEvent notification}<a name="line.287"></a>
<span class="sourceLineNo">288</span>     * of each local change.<a name="line.288"></a>
<span class="sourceLineNo">289</span>     * &lt;p&gt;<a name="line.289"></a>
<span class="sourceLineNo">290</span>     *<a name="line.290"></a>
<span class="sourceLineNo">291</span>     * &lt;p&gt;<a name="line.291"></a>
<span class="sourceLineNo">292</span>     * This method does nothing if the root is null.<a name="line.292"></a>
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<span class="sourceLineNo">295</span>     * @param snapshot snapshot containing new root (possibly null) and its version<a name="line.295"></a>
<span class="sourceLineNo">296</span>     * @param commitMessage message for the commit<a name="line.296"></a>
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<span class="sourceLineNo">306</span>        this.log.debug("committing new local root to branch `" + this.branch + "' (version " + snapshot.getVersion() + ")");<a name="line.306"></a>
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<span class="sourceLineNo">310</span>        } catch (Exception e) {<a name="line.310"></a>
<span class="sourceLineNo">311</span>            this.log.error("error committing local root to branch `" + this.branch + "'", e);<a name="line.311"></a>
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<span class="sourceLineNo">316</span>        if (commit == null) {<a name="line.316"></a>
<span class="sourceLineNo">317</span>            this.log.debug("commit of version " + snapshot.getVersion() + " resulted in no change on branch `" + this.branch + "'");<a name="line.317"></a>
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<span class="sourceLineNo">320</span>        this.log.info("committed root version " + snapshot.getVersion() + " as " + commit + " on branch `" + this.branch + "'");<a name="line.320"></a>
<span class="sourceLineNo">321</span><a name="line.321"></a>
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<span class="sourceLineNo">323</span>        if (!this.synchronize())<a name="line.323"></a>
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<span class="sourceLineNo">327</span>        final ArrayList&lt;T&gt; rootList = new ArrayList&lt;T&gt;(1);<a name="line.327"></a>
<span class="sourceLineNo">328</span>        String mergeCommit;<a name="line.328"></a>
<span class="sourceLineNo">329</span>        try {<a name="line.329"></a>
<span class="sourceLineNo">330</span>            mergeCommit = this.git.access(this.branch, new GitRepository.Accessor() {<a name="line.330"></a>
<span class="sourceLineNo">331</span>                @Override<a name="line.331"></a>
<span class="sourceLineNo">332</span>                public void accessWorkingCopy(File dir) {<a name="line.332"></a>
<span class="sourceLineNo">333</span>                    rootList.add(Synchronizer.this.readXMLFile(dir, false));<a name="line.333"></a>
<span class="sourceLineNo">334</span>                }<a name="line.334"></a>
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<span class="sourceLineNo">343</span>        try {<a name="line.343"></a>
<span class="sourceLineNo">344</span>            this.log.debug("applying merge commit " + mergeCommit + " to local persistent object");<a name="line.344"></a>
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<span class="sourceLineNo">346</span>            this.log.info("successfully applied commit " + mergeCommit + " to local persistent object as version " + version);<a name="line.346"></a>
<span class="sourceLineNo">347</span>        } catch (PersistentObjectVersionException e) {<a name="line.347"></a>
<span class="sourceLineNo">348</span>            this.log.debug("merged root is out of date (version " + e.getExpectedVersion() + " &lt; " + e.getActualVersion()<a name="line.348"></a>
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<span class="sourceLineNo">356</span>     * Read the persistent object root value that is currently committed to our local branch.<a name="line.356"></a>
<span class="sourceLineNo">357</span>     * This method can be used after a positive result from {@link #synchronize} to access the<a name="line.357"></a>
<span class="sourceLineNo">358</span>     * updated root.<a name="line.358"></a>
<span class="sourceLineNo">359</span>     *<a name="line.359"></a>
<span class="sourceLineNo">360</span>     * @return committed root<a name="line.360"></a>
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<span class="sourceLineNo">367</span>            public void accessWorkingCopy(File dir) {<a name="line.367"></a>
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<span class="sourceLineNo">375</span>     * Commit the given root to our {@code git(1)} repository.<a name="line.375"></a>
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<span class="sourceLineNo">377</span>     * &lt;p&gt;<a name="line.377"></a>
<span class="sourceLineNo">378</span>     * If the local branch does not already exist, it will be created.<a name="line.378"></a>
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<span class="sourceLineNo">381</span>     * @param root persistent object root<a name="line.381"></a>
<span class="sourceLineNo">382</span>     * @param commitMessage message for the commit<a name="line.382"></a>
<span class="sourceLineNo">383</span>     * @return new commit ID if commit occurred, or null if {@code root} was identical to the already-committed head of our branch<a name="line.383"></a>
<span class="sourceLineNo">384</span>     * @throws IllegalArgumentException if {@code root} is null<a name="line.384"></a>
<span class="sourceLineNo">385</span>     * @throws IllegalArgumentException if {@code commitMessage} is null<a name="line.385"></a>
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<span class="sourceLineNo">387</span>    protected synchronized String commit(final T root, String commitMessage) {<a name="line.387"></a>
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<span class="sourceLineNo">389</span>        // Sanity check<a name="line.389"></a>
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<span class="sourceLineNo">391</span>            throw new IllegalArgumentException("null root");<a name="line.391"></a>
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<span class="sourceLineNo">393</span>            throw new IllegalArgumentException("null commitMessage");<a name="line.393"></a>
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<span class="sourceLineNo">397</span><a name="line.397"></a>
<span class="sourceLineNo">398</span>        // Get previous commit ID<a name="line.398"></a>
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<span class="sourceLineNo">400</span><a name="line.400"></a>
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<span class="sourceLineNo">402</span>        this.log.debug("committing root to local branch `" + this.branch + "'");<a name="line.402"></a>
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<span class="sourceLineNo">404</span>            @Override<a name="line.404"></a>
<span class="sourceLineNo">405</span>            public void accessWorkingCopy(File dir) {<a name="line.405"></a>
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<span class="sourceLineNo">407</span>                  Synchronizer.this.getXMLFile(dir));<a name="line.407"></a>
<span class="sourceLineNo">408</span>            }<a name="line.408"></a>
<span class="sourceLineNo">409</span>        }, commitMessage);<a name="line.409"></a>
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<span class="sourceLineNo">411</span>        // Report results<a name="line.411"></a>
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<span class="sourceLineNo">415</span>    /**<a name="line.415"></a>
<span class="sourceLineNo">416</span>     * Synchronize what we have previously committed with our peers' latest information.<a name="line.416"></a>
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<span class="sourceLineNo">418</span>     * &lt;p&gt;<a name="line.418"></a>
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<span class="sourceLineNo">420</span>     * ensuring that the merge always yeilds a root that validates. If the fetch fails for<a name="line.420"></a>
<span class="sourceLineNo">421</span>     * one or more remotes, an error is logged and synchronization proceeds anyway.<a name="line.421"></a>
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<span class="sourceLineNo">424</span>     * &lt;p&gt;<a name="line.424"></a>
<span class="sourceLineNo">425</span>     * If the local branch does not already exist, it will be created.<a name="line.425"></a>
<span class="sourceLineNo">426</span>     * &lt;/p&gt;<a name="line.426"></a>
<span class="sourceLineNo">427</span>     *<a name="line.427"></a>
<span class="sourceLineNo">428</span>     * &lt;p&gt;<a name="line.428"></a>
<span class="sourceLineNo">429</span>     * This method does not affect the {@link PersistentObject} associated with this instance;<a name="line.429"></a>
<span class="sourceLineNo">430</span>     * the caller is responsible for doing that if necessary (i.e., when true is returned).<a name="line.430"></a>
<span class="sourceLineNo">431</span>     * &lt;/p&gt;<a name="line.431"></a>
<span class="sourceLineNo">432</span>     *<a name="line.432"></a>
<span class="sourceLineNo">433</span>     * &lt;p&gt;<a name="line.433"></a>
<span class="sourceLineNo">434</span>     * This method delegates to {@link #merge merge} to do the actual merging.<a name="line.434"></a>
<span class="sourceLineNo">435</span>     * &lt;/p&gt;<a name="line.435"></a>
<span class="sourceLineNo">436</span>     *<a name="line.436"></a>
<span class="sourceLineNo">437</span>     * @return true if one or more non-trivial merges ocurred, false if we were already up-to-date<a name="line.437"></a>
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<span class="sourceLineNo">442</span>        this.log.debug("beginning synchronization with remotes: " + this.remotes);<a name="line.442"></a>
<span class="sourceLineNo">443</span>        try {<a name="line.443"></a>
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<span class="sourceLineNo">445</span>        } catch (GitException e) {<a name="line.445"></a>
<span class="sourceLineNo">446</span>            this.log.info("pre-synchronize git fetch failed on one or more remotes; proceeding anyway");<a name="line.446"></a>
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<span class="sourceLineNo">453</span>        int numMerges = 0;<a name="line.453"></a>
<span class="sourceLineNo">454</span>        int numFails = 0;<a name="line.454"></a>
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<span class="sourceLineNo">459</span>            final String remoteRef = "refs/remotes/" + remote + "/" + this.branch;<a name="line.459"></a>
<span class="sourceLineNo">460</span>            if (!this.git.getRepoFile(remoteRef).exists()) {<a name="line.460"></a>
<span class="sourceLineNo">461</span>                this.log.debug("remote `" + remote + "' branch `" + this.branch + "' does not exist yet, skipping this remote");<a name="line.461"></a>
<span class="sourceLineNo">462</span>                continue;<a name="line.462"></a>
<span class="sourceLineNo">463</span>            }<a name="line.463"></a>
<span class="sourceLineNo">464</span>            final String remoteCommit = this.git.followReference(remoteRef);<a name="line.464"></a>
<span class="sourceLineNo">465</span><a name="line.465"></a>
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<span class="sourceLineNo">468</span>            final String localCommit = this.git.followReference(localRef);<a name="line.468"></a>
<span class="sourceLineNo">469</span><a name="line.469"></a>
<span class="sourceLineNo">470</span>            // Compare trees for equality<a name="line.470"></a>
<span class="sourceLineNo">471</span>            if (this.git.equalTrees(localCommit, remoteCommit)) {<a name="line.471"></a>
<span class="sourceLineNo">472</span>                this.log.debug("remote `" + remote + "' commit " + remoteCommit + " matches our branch `"<a name="line.472"></a>
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<span class="sourceLineNo">476</span><a name="line.476"></a>
<span class="sourceLineNo">477</span>            // Attempt merge<a name="line.477"></a>
<span class="sourceLineNo">478</span>            this.log.info("merging remote `" + remote + "' commit " + remoteCommit + " with local commit " + localCommit);<a name="line.478"></a>
<span class="sourceLineNo">479</span>            final String commit = this.merge(remote, localCommit, remoteCommit, this.branch);<a name="line.479"></a>
<span class="sourceLineNo">480</span>            if (commit == null) {<a name="line.480"></a>
<span class="sourceLineNo">481</span>                numFails++;<a name="line.481"></a>
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<span class="sourceLineNo">484</span><a name="line.484"></a>
<span class="sourceLineNo">485</span>            // Was a non-trivial merge required?<a name="line.485"></a>
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<span class="sourceLineNo">490</span>        // Done<a name="line.490"></a>
<span class="sourceLineNo">491</span>        this.log.debug("completed synchronization with remotes " + this.remotes<a name="line.491"></a>
<span class="sourceLineNo">492</span>          + " resulting in " + numMerges + " non-trivial merge(s) and " + numFails + " merge failure(s)");<a name="line.492"></a>
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<span class="sourceLineNo">497</span>     * Attempt to merge a local and remote commit and commit the result to the specified branch.<a name="line.497"></a>
<span class="sourceLineNo">498</span>     *<a name="line.498"></a>
<span class="sourceLineNo">499</span>     * &lt;p&gt;<a name="line.499"></a>
<span class="sourceLineNo">500</span>     * The implementation in {@link Synchronizer} attempts to merge the files in an automated way<a name="line.500"></a>
<span class="sourceLineNo">501</span>     * using git's patience merge algorithm.<a name="line.501"></a>
<span class="sourceLineNo">502</span>     * &lt;/p&gt;<a name="line.502"></a>
<span class="sourceLineNo">503</span>     *<a name="line.503"></a>
<span class="sourceLineNo">504</span>     * &lt;p&gt;<a name="line.504"></a>
<span class="sourceLineNo">505</span>     * In case of conflicts, {@link #chooseConflictWinner chooseConflictWinner()},<a name="line.505"></a>
<span class="sourceLineNo">506</span>     * {@link #handleConflictOverride handleConflictOverride()} and/or<a name="line.506"></a>
<span class="sourceLineNo">507</span>     * {@link #handleImpossibleMerge handleImpossibleMerge()} is invoked as appropriate.<a name="line.507"></a>
<span class="sourceLineNo">508</span>     * &lt;/p&gt;<a name="line.508"></a>
<span class="sourceLineNo">509</span>     *<a name="line.509"></a>
<span class="sourceLineNo">510</span>     * @param remote name of the remote being merged<a name="line.510"></a>
<span class="sourceLineNo">511</span>     * @param localCommit local commit name (SHA-1 hash)<a name="line.511"></a>
<span class="sourceLineNo">512</span>     * @param remoteCommit remote commit name (SHA-1 hash)<a name="line.512"></a>
<span class="sourceLineNo">513</span>     * @param commitBranch branch to commit merged result to<a name="line.513"></a>
<span class="sourceLineNo">514</span>     * @return commit name (SHA-1 hash) if the merge succeeded, null if the merge failed<a name="line.514"></a>
<span class="sourceLineNo">515</span>     */<a name="line.515"></a>
<span class="sourceLineNo">516</span>    protected String merge(String remote, String localCommit, String remoteCommit, String commitBranch) {<a name="line.516"></a>
<span class="sourceLineNo">517</span><a name="line.517"></a>
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<span class="sourceLineNo">520</span><a name="line.520"></a>
<span class="sourceLineNo">521</span>        // Build merge strategy list<a name="line.521"></a>
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<span class="sourceLineNo">523</span>          MergeStrategy.RECURSIVE_PATIENCE,<a name="line.523"></a>
<span class="sourceLineNo">524</span>          iWin ? MergeStrategy.RECURSIVE_PATIENCE_OURS : MergeStrategy.RECURSIVE_PATIENCE_THEIRS,<a name="line.524"></a>
<span class="sourceLineNo">525</span>          iWin ? MergeStrategy.RECURSIVE_OURS : MergeStrategy.RECURSIVE_THEIRS,<a name="line.525"></a>
<span class="sourceLineNo">526</span>          iWin ? MergeStrategy.OURS : MergeStrategy.THEIRS<a name="line.526"></a>
<span class="sourceLineNo">527</span>        };<a name="line.527"></a>
<span class="sourceLineNo">528</span><a name="line.528"></a>
<span class="sourceLineNo">529</span>        // Attempt merges using successively less "mergey" strategies<a name="line.529"></a>
<span class="sourceLineNo">530</span>        for (MergeStrategy strategy : strategyList) {<a name="line.530"></a>
<span class="sourceLineNo">531</span><a name="line.531"></a>
<span class="sourceLineNo">532</span>            // Attempt merge<a name="line.532"></a>
<span class="sourceLineNo">533</span>            this.log.debug("attempting merge of remote `" + remote + "' commit " + remoteCommit<a name="line.533"></a>
<span class="sourceLineNo">534</span>              + " with local commit " + localCommit + " using strategy " + strategy);<a name="line.534"></a>
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<span class="sourceLineNo">538</span>                    @Override<a name="line.538"></a>
<span class="sourceLineNo">539</span>                    public void accessWorkingCopy(File dir) {<a name="line.539"></a>
<span class="sourceLineNo">540</span>                        Synchronizer.this.log.debug("validating merged file `" + Synchronizer.this.getXMLFile(dir) + "'");<a name="line.540"></a>
<span class="sourceLineNo">541</span>                        Synchronizer.this.readXMLFile(dir, true);<a name="line.541"></a>
<span class="sourceLineNo">542</span>                    }<a name="line.542"></a>
<span class="sourceLineNo">543</span>                }, "Merged remote `" + remote + "' commit " + remoteCommit + " using strategy " + strategy);<a name="line.543"></a>
<span class="sourceLineNo">544</span>            } catch (GitMergeConflictException e) {<a name="line.544"></a>
<span class="sourceLineNo">545</span>                this.log.debug("merge using strategy " + strategy + " failed with conflict(s)");<a name="line.545"></a>
<span class="sourceLineNo">546</span>                continue;<a name="line.546"></a>
<span class="sourceLineNo">547</span>            } catch (PersistentObjectException e) {<a name="line.547"></a>
<span class="sourceLineNo">548</span>                this.log.debug("merge using strategy " + strategy + " did not validate: " + e);<a name="line.548"></a>
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<span class="sourceLineNo">551</span><a name="line.551"></a>
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<span class="sourceLineNo">553</span>            if (commit.equals(localCommit)) {<a name="line.553"></a>
<span class="sourceLineNo">554</span>                this.log.debug("merge of remote `" + remote + "' commit " + remoteCommit + " with local commit "<a name="line.554"></a>
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<span class="sourceLineNo">556</span>            } else {<a name="line.556"></a>
<span class="sourceLineNo">557</span>                this.log.debug("successfully merged remote `" + remote + "' commit " + remoteCommit + " with local commit "<a name="line.557"></a>
<span class="sourceLineNo">558</span>                  + localCommit + " using strategy " + strategy + " resulting in commit " + commit);<a name="line.558"></a>
<span class="sourceLineNo">559</span>            }<a name="line.559"></a>
<span class="sourceLineNo">560</span><a name="line.560"></a>
<span class="sourceLineNo">561</span>            // Log a warning if some of our local changes got overridden by remote<a name="line.561"></a>
<span class="sourceLineNo">562</span>            switch (strategy) {<a name="line.562"></a>
<span class="sourceLineNo">563</span>            case RECURSIVE_PATIENCE_THEIRS:<a name="line.563"></a>
<span class="sourceLineNo">564</span>            case RECURSIVE_THEIRS:<a name="line.564"></a>
<span class="sourceLineNo">565</span>                this.handleConflictOverride(remote, localCommit, remoteCommit, strategy);<a name="line.565"></a>
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<span class="sourceLineNo">567</span>            default:<a name="line.567"></a>
<span class="sourceLineNo">568</span>                break;<a name="line.568"></a>
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<span class="sourceLineNo">570</span><a name="line.570"></a>
<span class="sourceLineNo">571</span>            // Done<a name="line.571"></a>
<span class="sourceLineNo">572</span>            return commit;<a name="line.572"></a>
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<span class="sourceLineNo">574</span><a name="line.574"></a>
<span class="sourceLineNo">575</span>        // Nothing worked - so we must be running different versions of the application<a name="line.575"></a>
<span class="sourceLineNo">576</span>        this.handleImpossibleMerge(remote, localCommit, remoteCommit);<a name="line.576"></a>
<span class="sourceLineNo">577</span>        return null;<a name="line.577"></a>
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<span class="sourceLineNo">579</span><a name="line.579"></a>
<span class="sourceLineNo">580</span>    /**<a name="line.580"></a>
<span class="sourceLineNo">581</span>     * Choose which commit should "win" in case there is a conflict between two commits.<a name="line.581"></a>
<span class="sourceLineNo">582</span>     *<a name="line.582"></a>
<span class="sourceLineNo">583</span>     * &lt;p&gt;<a name="line.583"></a>
<span class="sourceLineNo">584</span>     * It is imperative that this method &lt;b&gt;only&lt;/b&gt; depend on information associated with the given commits.<a name="line.584"></a>
<span class="sourceLineNo">585</span>     * In particular, it must not depend on which node it is running on. This ensures that all nodes come<a name="line.585"></a>
<span class="sourceLineNo">586</span>     * to the same conclusion and therefore produce the same outcome when merging.<a name="line.586"></a>
<span class="sourceLineNo">587</span>     * &lt;/p&gt;<a name="line.587"></a>
<span class="sourceLineNo">588</span>     *<a name="line.588"></a>
<span class="sourceLineNo">589</span>     * &lt;p&gt;<a name="line.589"></a>
<span class="sourceLineNo">590</span>     * The implementation in {@link Synchronizer} chooses the commit with the later timestamp, or if both commits<a name="line.590"></a>
<span class="sourceLineNo">591</span>     * have the same timestamp, then the commit with the lexicographically higher SHA-1 checksum.<a name="line.591"></a>
<span class="sourceLineNo">592</span>     * &lt;/p&gt;<a name="line.592"></a>
<span class="sourceLineNo">593</span>     *<a name="line.593"></a>
<span class="sourceLineNo">594</span>     * @param commit1 first commit ID<a name="line.594"></a>
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<span class="sourceLineNo">597</span>     */<a name="line.597"></a>
<span class="sourceLineNo">598</span>    protected boolean chooseConflictWinner(String commit1, String commit2) {<a name="line.598"></a>
<span class="sourceLineNo">599</span>        final Date date1 = this.git.getAuthorDate(commit1);<a name="line.599"></a>
<span class="sourceLineNo">600</span>        final Date date2 = this.git.getAuthorDate(commit2);<a name="line.600"></a>
<span class="sourceLineNo">601</span>        return date1.compareTo(date2) &gt; 0 || (date1.compareTo(date2) == 0 &amp;&amp; commit1.compareTo(commit2) &gt; 0);<a name="line.601"></a>
<span class="sourceLineNo">602</span>    }<a name="line.602"></a>
<span class="sourceLineNo">603</span><a name="line.603"></a>
<span class="sourceLineNo">604</span>    /**<a name="line.604"></a>
<span class="sourceLineNo">605</span>     * Handle a situation where some of our local changes were overridden due to merge conflicts, but<a name="line.605"></a>
<span class="sourceLineNo">606</span>     * in the end we were able to produce a valid root.<a name="line.606"></a>
<span class="sourceLineNo">607</span>     *<a name="line.607"></a>
<span class="sourceLineNo">608</span>     * &lt;p&gt;<a name="line.608"></a>
<span class="sourceLineNo">609</span>     * The implementation in {@link Synchronizer} just logs a warning message.<a name="line.609"></a>
<span class="sourceLineNo">610</span>     * &lt;/p&gt;<a name="line.610"></a>
<span class="sourceLineNo">611</span>     *<a name="line.611"></a>
<span class="sourceLineNo">612</span>     * @param remote name of the remote that overrode us<a name="line.612"></a>
<span class="sourceLineNo">613</span>     * @param localCommit our commit in the merge<a name="line.613"></a>
<span class="sourceLineNo">614</span>     * @param remoteCommit remote's commit in the merge<a name="line.614"></a>
<span class="sourceLineNo">615</span>     * @param strategy the strategy that was used to resolve the conflict<a name="line.615"></a>
<span class="sourceLineNo">616</span>     */<a name="line.616"></a>
<span class="sourceLineNo">617</span>    protected void handleConflictOverride(String remote, String localCommit, String remoteCommit, MergeStrategy strategy) {<a name="line.617"></a>
<span class="sourceLineNo">618</span>        this.log.warn("some changes in local commit " + localCommit + " have been overridden by changes from remote `"<a name="line.618"></a>
<span class="sourceLineNo">619</span>          + remote + "' commit " + remoteCommit + " using merge strategy " + strategy);<a name="line.619"></a>
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<span class="sourceLineNo">621</span><a name="line.621"></a>
<span class="sourceLineNo">622</span>    /**<a name="line.622"></a>
<span class="sourceLineNo">623</span>     * Handle a situation where all of the merge strategies failed to produce a valid root object.<a name="line.623"></a>
<span class="sourceLineNo">624</span>     * This can only happen when a remote node has different validation criteria than we do, for example,<a name="line.624"></a>
<span class="sourceLineNo">625</span>     * it is running a different version of the application.<a name="line.625"></a>
<span class="sourceLineNo">626</span>     *<a name="line.626"></a>
<span class="sourceLineNo">627</span>     * &lt;p&gt;<a name="line.627"></a>
<span class="sourceLineNo">628</span>     * The implementation in {@link Synchronizer} just logs a warning message.<a name="line.628"></a>
<span class="sourceLineNo">629</span>     * &lt;/p&gt;<a name="line.629"></a>
<span class="sourceLineNo">630</span>     *<a name="line.630"></a>
<span class="sourceLineNo">631</span>     * @param remote name of the remote that we are conflicting with<a name="line.631"></a>
<span class="sourceLineNo">632</span>     * @param localCommit our commit in the merge<a name="line.632"></a>
<span class="sourceLineNo">633</span>     * @param remoteCommit remote's commit in the merge<a name="line.633"></a>
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<span class="sourceLineNo">637</span>          + remoteCommit + "; are we running different application versions?");<a name="line.637"></a>
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<span class="sourceLineNo">639</span><a name="line.639"></a>
<span class="sourceLineNo">640</span>    /**<a name="line.640"></a>
<span class="sourceLineNo">641</span>     * Get the XML file.<a name="line.641"></a>
<span class="sourceLineNo">642</span>     *<a name="line.642"></a>
<span class="sourceLineNo">643</span>     * &lt;p&gt;<a name="line.643"></a>
<span class="sourceLineNo">644</span>     * To avoid race conditions, the file should only be accessed from within a {@link GitRepository.Accessor} callback.<a name="line.644"></a>
<span class="sourceLineNo">645</span>     * &lt;/p&gt;<a name="line.645"></a>
<span class="sourceLineNo">646</span>     *<a name="line.646"></a>
<span class="sourceLineNo">647</span>     * @param dir {@code git(1)} working directory root<a name="line.647"></a>
<span class="sourceLineNo">648</span>     */<a name="line.648"></a>
<span class="sourceLineNo">649</span>    protected File getXMLFile(File dir) {<a name="line.649"></a>
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<span class="sourceLineNo">653</span>    /**<a name="line.653"></a>
<span class="sourceLineNo">654</span>     * Read and (optionally) validate the XML file.<a name="line.654"></a>
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<span class="sourceLineNo">656</span>     * &lt;p&gt;<a name="line.656"></a>
<span class="sourceLineNo">657</span>     * To avoid race conditions, this method should only be invoked from within a {@link GitRepository.Accessor} callback.<a name="line.657"></a>
<span class="sourceLineNo">658</span>     * &lt;/p&gt;<a name="line.658"></a>
<span class="sourceLineNo">659</span>     *<a name="line.659"></a>
<span class="sourceLineNo">660</span>     * @param dir {@code git(1)} working directory root<a name="line.660"></a>
<span class="sourceLineNo">661</span>     * @param validate whether to also validate the file<a name="line.661"></a>
<span class="sourceLineNo">662</span>     */<a name="line.662"></a>
<span class="sourceLineNo">663</span>    protected T readXMLFile(File dir, boolean validate) {<a name="line.663"></a>
<span class="sourceLineNo">664</span>        return PersistentObject.read(this.persistentObject.getDelegate(), this.getXMLFile(dir), validate);<a name="line.664"></a>
<span class="sourceLineNo">665</span>    }<a name="line.665"></a>
<span class="sourceLineNo">666</span>}<a name="line.666"></a>
<span class="sourceLineNo">667</span><a name="line.667"></a>




























































</pre>
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